Comparison of A11 and I11 antibody specificity. A. Dot blots. Aβ monomer, Aβ prefibrillar oligomers (prepared in HFIP-H20, pH 2.5), Aβ fibrils and α-synuclein and IAPP prefibrillar oligomers were spotted on nitrocellulose strips and probed with A11, I11 and 6E10 as a control. A11 and I11 antibodies demonstrate the same specificity for prefibrillar oligomers and do not react with monomer or fibrils. 6E10 stains the Aβ-containing samples, including prefibrillar oligomers formed at acid pH. B. Western blots. Prefibrillar oligomer samples of calcitonin (Lane 1), insulin (Lane 2) and prion peptide 106–126 (Lane 3) were probed with A11 and I11, which give the same staining pattern.